Surfactant based small molecules for reducing aluminosilicate scale in the Bayer process

ABSTRACT

The invention provides methods and compositions for inhibiting the accumulation of DSP scale in the liquor circuit of Bayer process equipment. The method includes adding one or more GPS-surfactant based small molecules to the liquor fluid circuit. These scale inhibitors reduce DSP scale formation and thereby increase fluid throughput, increase the amount of time Bayer process equipment can be operational and reduce the need for expensive and dangerous acid washes of Bayer process equipment. As a result, the invention provides a significant reduction in the total cost of operating a Bayer process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 14/151,368, filed Jan. 9, 2014, issued as U.S. Pat. No.9,416,020, itself a continuation-in-part of U.S. patent application Ser.No. 13/403,282, filed Feb. 23, 2012, issued as U.S. Pat. No. 9,487,408,itself a continuation-in-part of U.S. patent application Ser. No.12/567,116, filed Sep. 25, 2009, issued as U.S. Pat. No. 8,545,776 thedisclosures of which are herein incorporated by reference in theirentireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

The invention relates to compositions, methods, and apparatuses forimproving treatment and inhibition of scale in various industrialprocess streams, in particular certain surfactant based small moleculesthat have been found to be particularly effective in treatingaluminosilicate scale in a Bayer process stream.

As described among other places in U.S. Pat. No. 6,814,873 the contentsof which are incorporated by reference in their entirety, the Bayerprocess is used to manufacture alumina from Bauxite ore. The processuses caustic solution to extract soluble alumina values from thebauxite. After dissolution of the alumina values from the bauxite andremoval of insoluble waste material from the process stream the solublealumina is precipitated as solid alumina trihydrate. The remainingcaustic solution known as “liquor” and/or “spent liquor” is thenrecycled back to earlier stages in the process and is used to treatfresh bauxite. It thus forms a fluid circuit. For the purposes of thisapplication, this description defines the term “liquor”. The recyclingof liquor within the fluid circuit however has its own complexities.

Bauxite often contains silica in various forms and amounts. Some of thesilica is unreactive so it does not dissolve and remains as solidmaterial within the Bayer circuit. Other forms of silica (for exampleclays) are reactive and dissolve in caustic when added into Bayerprocess liquors, thus increasing the silica concentration in the liquor.As liquor flows repeatedly through the circuit of the Bayer process, theconcentration of silica in the liquor further increases, eventually to apoint where it reacts with aluminum and soda to form insolublealuminosilicate particles. Aluminosilicate solid is observed in at leasttwo forms, sodalite and cancrinite. These and other forms ofaluminosilicate are commonly referred to, and for the purposes of thisapplication define, the terms “desilication product” or “DSP”.

DSP can have a formula of 3(Na₂O.Al₂O₃.2SiO₂.0-2 H₂O).2NaX where Xrepresents OH⁻, Cl⁻, CO₃ ²⁻, SO₄ ²⁻. Because DSP has an inversesolubility (precipitation increases at higher temperatures) and it canprecipitate as fine scales of hard insoluble crystalline solids, itsaccumulation in Bayer process equipment is problematic. As DSPaccumulates in Bayer process pipes, vessels, heat transfer equipment,and other process equipment, it forms flow bottlenecks and obstructionsand can adversely affect liquor throughput. In addition because of itsthermal conductivity properties, DSP scales on heat exchanger surfacesreduce the efficiency of heat exchangers.

These adverse effects are typically managed through a descaling regime,which involves process equipment being taken off line and the scalebeing physically or chemically treated and removed. A consequence ofthis type of regime is significant and regular periods of down-time forcritical equipment. Additionally as part of the descaling process theuse of hazardous concentrated acids such as sulfuric acid are oftenemployed and this constitutes an undesirable safety hazard.

Another way Bayer process operators manage the buildup of silicaconcentration in the liquor is to deliberately precipitate DSP as freecrystals rather than as scale. Typically a “desilication” step in theBayer process is used to reduce the concentration of silica in solutionby precipitation of silica as DSP, as a free precipitate. While suchdesilication reduces the overall silica concentration within the liquor,total elimination of all silica from solution is impractical andchanging process conditions within various parts of the circuit (forexample within heat exchangers) can lead to changes in the solubility ofDSP, resulting in consequent precipitation as scale.

Previous attempts at controlling and/or reducing DSP scale in the Bayerprocess have included adding polymer materials containing three alkyloxygroups bonded to one silicon atom as described in U.S. Pat. No.6,814,873 B2, US published applications 2004/0162406 A1, 2004/0011744A1, 2005/0010008 A2, international published application WO 2008/045677A1, and published article Max HTTM Sodalite Scale Inhibitor: PlantExperience and Impact on the Process, by Donald Spitzer et. al., Pages57-62, Light Metals 2008, (2008) all of whose contents are incorporatedby reference in their entirety.

Manufacturing and use of these trialkoxysilane-grafted polymers howevercan involve unwanted degrees of viscosity, making handling anddispersion of the polymer through the Bayer process liquor problematic.Other previous attempts to address foulant buildup are described in U.S.Pat. Nos. 5,650,072 and 5,314,626 both of which are incorporated byreference in their entirety.

Thus while a range of methods are available to Bayer process operatorsto manage and control DSP scale formation, there is a clear need for,and utility in, an improved method of preventing or reducing DSP scaleformation on Bayer process equipment. The art described in this sectionis not intended to constitute an admission that any patent, publicationor other information referred to herein is “prior art” with respect tothis invention, unless specifically designated as such. In addition,this section should not be construed to mean that a search has been madeor that no other pertinent information as defined in 37 C.F.R. § 1.56(a)exists.

BRIEF SUMMARY OF THE INVENTION

To satisfy the long-felt but unsolved needs identified above, at leastone embodiment of the invention is directed towards a method forreducing siliceous scale in a Bayer process comprising the step ofadding to a Bayer liquor an aluminosilicate scale reducing amount of anon-polymeric reaction product resulting from the reaction of: a) asurfactant and b) a GPS.

The non-polymeric reaction product may be a resultant from the reactionof items further comprising one item selected from the group consistingof at least one: hydrophobe, amine binder, epoxide binder, and anycombination thereof. The GPS may be 3-glycidoxypropyltrimethoxysilane.The surfactant may be one selected from the group consisting of:ethoxylated fatty alcohols, ethoxylated fatty amines, fatty amines,G12A7, G12A4, G17A3, G9A6, G9A8, 18M20, 18M2, 16M2, DPD, OPD, OLA, andany combination thereof. The epoxide binder may be a molecule accordingto formulas (I), (II), and any combination thereof:

The hydrophobe may be a C8-C10 aliphatic glycidyl ether. The reactionproduct may have a molecular weight of less than 500 daltons. Thereaction product may be according to the formula illustrated in FIG. 1,FIG. 2, and/or may be Product P, Product U, and/or Product HS.

The reaction product may be formed at least in part according to one ofthe methods selected from the group consisting of Methods: I, II, III,IV, V, VI, VII, VIII, IX, X, XI, XII, and XIII, and any combinationthereof. The amine binder may be one selected from the list consistingof: tetraethylenepentamine and ethylenediamine.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described withspecific reference being made to the drawings in which:

FIG. 1 is an illustration of the formula of reaction product X.

FIG. 2 is an illustration of the formula of reaction product BB.

FIG. 3 is a first table of Formula types used in the invention.

FIG. 4 is a second table of Formula types used in the invention.

FIG. 5 is a third table of Formula types used in the invention.

FIG. 6 is a fourth table of Formula types used in the invention

FIG. 7 is an illustration of SEM (Scanning Electron Microscope) analysisdemonstrating the efficacy of the invention.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated. Thedrawings are only an exemplification of the principles of the inventionand are not intended to limit the invention to the particularembodiments illustrated.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are provided to determine how terms used inthis application, and in particular how the claims, are to be construed.The organization of the definitions is for convenience only and is notintended to limit any of the definitions to any particular category.

“Polymer” means a chemical compound comprising essentially repeatingstructural units each containing two or more atoms. While many polymershave large molecular weights of greater than 500, some polymers such aspolyethylene can have molecular weights of less than 500. Polymerincludes copolymers and homo polymers.

“Small molecule” means a chemical compound comprising essentiallynon-repeating structural units. Because an oligomer (with more than 10repeating units) and a polymer are essentially comprised of repeatingstructural units, they are not small molecules. Small molecules can havemolecular weights above and below 500. The terms “small molecule” and“polymer” are mutually exclusive.

“Foulant” means a material deposit that accumulates on equipment duringthe operation of a manufacturing and/or chemical process which may beunwanted and which may impair the cost and/or efficiency of the process.DSP is a type of foulant.

“Amine” means a molecule containing one or more nitrogen atoms andhaving at least one secondary amine or primary amine group. By thisdefinition, monoamines such as dodecylamine, diamines such ashexanediamine, and triamines such as diethylenetriamine, are all amines.

“GPS” is glycidoxyalkyltrimethoxysilane which includes3-glycidoxypropyltrimethoxysilane, one possible formula for GPS can berepresented by the structure:

“Ethoxylated Alcohol” means an alcohol according to the formula:R—(EO)_(n)—OHwherein EO is an ethoxy group (—OCH2CH2—) and n is an integer within therange 1-50.

“Ethoxylated Amine” means an amine according to the formula:

wherein EO is an ethoxy group (—OCH2CH2—), m is an integer within therange 1-50, and n is an integer within the range 1-50.

“G12A7” means a C12-C14 non-ionic alcohol ethoxylate surfactant, arepresentative example of which is Teric G12A7 sold by Huntsman.

“G12A4” means a C12-C14 non-ionic alcohol ethoxylate surfactant, arepresentative example of which is Teric G12A4 sold by Huntsman.

“G17A3” means a C16-C18 straight chain non-ionic alcohol ethoxylatesurfactant, a representative example of which is Teric G17A3 sold byHuntsman.

“G9A6” means a C9-C11 straight chain non-ionic alcohol ethoxylatesurfactant, a representative example of which is Teric G9A6 sold byHuntsman.

“G9A8” means a C9-C11 straight chain non-ionic alcohol ethoxylatesurfactant, a representative example of which is Teric G9A8 sold byHuntsman.

“18M20” means a C18-C22 alkyl amine ethoxylate surfactant, arepresentative example of which is Teric 18M20 sold by Huntsman.

“18M2” means a C18-C22 alkyl amine ethoxylate surfactant, arepresentative example of which is Teric 18M2 sold by Huntsman.

“16M2” means a C16-C18 alkyl amine ethoxylate surfactant, arepresentative example of which is Teric 16M2 sold by Huntsman.

“TAM5” means tallow alkyl amine ethoxylate surfactant, a representativeexample of which is Agnique TAM5 sold by Cognis.

“DPD” means dodecyl-1,3-propanediamine

“EGDGE” means ethylene glycol diglycidylether

“OPD” means oleyl-1,3-propanediamine

“EPI” means epichlorohydrin

“OA” means octylamine

“ED” means ethylenediamine

“OLA” means oleylamine

“TEPA” means tetraethylenepentamine

“AGE” means C8-C10 aliphatic glycidyl ether

“Alkyloxy” means having the structure of OX where X is a hydrocarbon andO is oxygen. It can also be used interchangeably with the term “alkoxy”.Typically in this application, the oxygen is bonded both to the X groupas well as to a silicon atom of the small molecule. When X is C₁ thealkyloxy group consists of a methyl group bonded to the oxygen atom.When X is C₂ the alkyloxy group consists of an ethyl group bonded to theoxygen atom. When X is C₃ the alkyloxy group consists of a propyl groupbonded to the oxygen atom. When X is C₄ the alkyloxy group consists of abutyl group bonded to the oxygen atom. When X is C₅ the alkyloxy groupconsists of a pentyl group bonded to the oxygen atom. When X is C₆ thealkyloxy group consists of a hexyl group bonded to the oxygen atom.

“Monoalkyloxy” means that attached to a silicon atom is one alkyloxygroup.

“Dialkyloxy” means that attached to a silicon atom are two alkyloxygroups.

“Trialkyloxy” means that attached to a silicon atom are three alkyloxygroups.

“Synthetic Liquor” or “Synthetic Spent Liquor” is a laboratory createdliquid used for experimentation whose composition in respect to alumina,soda, and caustic corresponds with the liquor produced by recyclingthrough the Bayer process.

“Bayer Liquor” is actual liquor that has run through a Bayer process inan industrial facility.

“Separation” means a mass transfer process that converts a mixture ofsubstances into two or more distinct product mixtures, at least one ofwhich is enriched in one or more of the mixture's constituents, itincludes but is not limited to such processes as: Adsorption,Centrifugation, cyclonic separation, density based separation,Chromatography, Crystallization, Decantation, Distillation, Drying,Electrophoresis, Elutriation, Evaporation, Extraction, Leachingextraction, Liquid-liquid extraction, Solid phase extraction, Flotation,Dissolved air flotation, Froth flotation, Flocculation, Filtration, Meshfiltration, membrane filtration, microfiltration, ultrafiltration,nanofiltration, reverse osmosis, Fractional distillation, Fractionalfreezing, Magnetic separation, Precipitation, Recrystallization,Sedimentation, Gravity separation, Sieving, Stripping, Sublimation,Vapor-liquid separation, Winnowing, Zone refining, and any combinationthereof.

“Thickener” or “Settler” means a vessel used to effect a solid-liquidseparation of a slurry, often with the addition of flocculants, thevessel constructed and arranged to receive a slurry, retain the slurryfor a period of time sufficient to allow solid portions of the slurry tosettle downward (underflow) away from a more liquid portion of theslurry (overflow), decant the overflow, and remove the underflow.Thickener underflow and thickener overflow are often passed on tofilters to further separate solids from liquids.

In the event that the above definitions or a description statedelsewhere in this application is inconsistent with a meaning (explicitor implicit) which is commonly used, in a dictionary, or stated in asource incorporated by reference into this application, the applicationand the claim terms in particular are understood to be construedaccording to the definition or description in this application, and notaccording to the common definition, dictionary definition, or thedefinition that was incorporated by reference. In light of the above, inthe event that a term can only be understood if it is construed by adictionary, if the term is defined by the Kirk-Othmer Encyclopedia ofChemical Technology, 5th Edition, (2005), (Published by Wiley, John &Sons, Inc.) this definition shall control how the term is to be definedin the claims.

In the Bayer process for manufacturing alumina, bauxite ore passesthrough a grinding stage and alumina, together with some impuritiesincluding silica, are dissolved in added liquor. The mixture thentypically passes through a desilication stage where silica isdeliberately precipitated as DSP to reduce the amount of silica insolution. The slurry is passed on to a digestion stage where anyremaining reactive silica dissolves, thus again increasing theconcentration of silica in solution which may subsequently form more DSPas the process temperature increases. The liquor is later separated fromundissolved solids, and alumina is recovered by precipitation asgibbsite. The spent liquor completes its circuit as it passes through aheat exchanger and back into the grinding stage. DSP scale accumulatesthroughout the Bayer process but particularly at the digestion stage andmost particularly at or near the heat exchanger, where the recycledliquor passes through.

In this invention, it was discovered that dosing of various types ofsmall molecule based products can reduce the amount of DSP scale formed.The small molecules are reaction products of surfactants with GPS andoptionally also with one or more of: hydrophobes, amine binders, epoxidebinders, and any combination thereof. FIG. 1 and FIG. 2 showrepresentative structures of small molecules constituted by combinationsof surfactant, GPS and epoxide binder (FIG. 1) and surfactant, GPS,epoxide binder and amine binder (FIG. 2) and which are examples of thepossible reaction product combinations encompassed by this embodiment.In at least one embodiment of the invention, an effective concentrationof the small molecule product is added to some point or stage in theliquor circuit of the Bayer process, which minimizes or prevents theaccumulation of DSP on vessels or equipment along the liquor circuit.

As described in U.S. Pat. No. 8,545,776 the small molecule DG12 is anexample of a small molecule which is a reaction product of a surfactantand GPS. Similarly small molecule TG14 also in U.S. Pat. No. 8,545,776,and the various small molecules such as GEN1, GEN2, and GEN3 aredescribed in US Published Patent Applications 2011/0212006 and2012/0148462 are reaction products of some of these items. In at leastone embodiment the invention excludes TG14, DG12, GEN1, GEN2, and GEN3.

In at least one embodiment the reaction product is formed at least inpart by allowing two or more of the reactants to contact each other fora period of time between 1 minute and 55 days, and/or by allowing thereactants to contact each other at a temperature of between 20° C. and500° C. The invention encompasses adding any of some or all thereactants to the reaction simultaneously and/or in any sequential order.Any portion of the reaction may occur within one or more of: a liquidmedium, a water medium, in the presence of acid and/or base, and orunder acidic, basic, or neutral conditions. Any portion of the reactionmay occur at least in part in the presence of one or more catalysts.

In at least one embodiment the surfactant includes but is not limited toone selected from the list consisting of: ethoxylated fatty alcohols,ethoxylated fatty amines, fatty amines, G12A7, G12A4, G17A3, G9A6, G9A8,18M20, 18M2, 16M2, DPD, OPD, OLA, and any combination thereof. FIG. 3,FIG. 4, FIG. 5 and FIG. 6 are tables illustrating some of the possiblereaction product combinations encompassed by this embodiment.

In at least one embodiment the epoxide binder is according to one ormore of the formulas (I) and (II):

In at least one embodiment the hydrophobe is a C8-C10 aliphatic glycidylether. The hydrophobe may be may be described as a linear or branched,aromatic or aliphatic hydrocarbon chain which may optionally contain anether linkage or additional functional end group such as an epoxidewhich allows the hydrophobe to be reacted with and attached to othermolecules. The hydrocarbon chain may consist of between 3 and 50 carbonatoms

In at least one embodiment the hydrophobe is according to formula (III)where R′ is a linear or branched hydrocarbon chain containing at least 3carbon atoms:

In at least one embodiment, the amine binder is selected from a linearor branched, aliphatic or cycloaliphatic monoamines, diamines,triamines, butamines, and pentamines. The total number of carbon atomsin the amine is preferred to be less than 30 and more preferred to beless than 20. In at least one embodiment the amine is selected from alist consisting of: tetraethylene pentamine, ethylene diamene, and anycombination thereof.

In at least one embodiment, an amine small molecule is reacted with both3-glycidoxypropyltrialkoxysilane (GPS) and a hydrophobic molecule toform a DSP inhibition composition. The hydrophobic molecule is anamine-reactive compound having an amine-reactive functional group suchas glycidyl, chloro, bromo, or isocyanato groups. Besides theamine-reactive group, the hydrophobic molecule has at least one C₃-C₂₂hydrophobic carbon chain, aromatic or aliphatic, linear or branched.

In at least one embodiment, the amine molecule is selected from linearor branched, aliphatic or cycloaliphatic monoamines or diamines. Thetotal number of carbon atoms in the amine is preferred to be less than30 and more preferred to be less than 20.

In at least one embodiment the amine is selected from a list consistingof: isophoronediamine, xylenediamine, bis(aminomethyl)cyclohexane,hexanediamine, C,C,C-trimethylhexanediamine, methylenebis(aminocyclohexane), saturated fatty amines, unsaturated fatty aminessuch as oleylamine and soyamine, N-fatty-1,3-propanediamine such ascocoalkylpropanediamine, oleylpropanediamine, dodecylpropanediamine,hydrogenized tallowalkylpropanediamine, and tallowalkylpropanediamineand any combination thereof.

In at least one embodiment the reaction product is Product P, which is areaction product of GPS with a surfactant having a formula of:

In at least one embodiment the reaction product is Product U, which is areaction product of GPS with a surfactant and a hydrophobe having aformula of:

In at least one embodiment the reaction product is Product X, which is areaction product of GPS with a surfactant, a hydrophobe and an epoxidebinder having a formula illustrated in FIG. 1.

In at least one embodiment the reaction product is Product BB, which isa reaction product of GPS with a surfactant, a hydrophobe, an epoxidebinder and an amine binder having a formula illustrated in FIG. 2.

In at least one embodiment the reaction conditions results in theformation of two or more of the aforementioned and incorporated reactionproducts. In at least one embodiment the composition introduced toaddress DSP contains one, two, or more of the aforementioned andincorporated reaction products.

In at least one embodiment the resulting surfactant based smallmolecules are added to a dilute caustic solution prior to addition tothe process stream.

These small molecules reduce the amount of DSP scale formed and therebyprevents its accumulation on Bayer process equipment.

The effectiveness of these small molecules was unexpected as the priorart teaches that only high molecular weight polymers are effective.Polymer effectiveness was presumed to depend on their hydrophobic natureand their size. This was confirmed by the fact that cross-linkedpolymers are even more effective than single chain polymers. As a resultit was assumed that small molecules only serve as building blocks forthese polymers and are not effective in their own right. (WO 2008/045677[0030]). Furthermore, the scientific literature states “small moleculescontaining” . . . “[an] Si—O₃ grouping are not effective in preventingsodalite scaling” . . . because . . . “[t]he bulky group” . . . “isessential [in] keeping the molecule from being incorporated into thegrowing sodalite.” Page 57 ¶ 9 Light Metals 2008, (2008). However it hasrecently been discovered that in fact, as further explained in theprovided examples, small molecules such as those described herein areactually effective at reducing DSP scale.

It is believed that there are at least three advantages to using a smallmolecule-based inhibitor as opposed to a polymeric inhibitor withmultiple repeating units of silane and hydrophobes. A first advantage isthat the smaller molecular weight of the product means that there are alarger number of active, inhibiting moieties available around the DSPseed crystal sites at the DSP formation stage. A second advantage isthat the lower molecular weight allows for an increased rate ofdiffusion of the inhibitor, which in turn favors fast attachment of theinhibitor molecules onto DSP seed crystals. A third advantage is thatthe lower molecular weight avoids high product viscosity and so makeshandling and injection into the Bayer process stream more convenient andeffective.

In at least one embodiment DSP scale is addressed using one or more ofthe compositions and/or methods of application described in U.S. patentapplications Ser. Nos. 13/035,124, 13/403,282, 13/791,577, 14/011,051,U.S. Pat. Nos. 5,314,626, 6,814,873, 7,390,415, 7,442,755, 7,763,698,International Patent Applications WO 02/070411, WO 2008/045677, WO2012/115769, and US Published Patent Applications 2004/0162406,2004/0011744, 2010/0256317, 2011/0076209, 2011/0212006, and2012/0148462.

Examples

The foregoing may be better understood by reference to the followingexamples, which are presented for purposes of illustration and are notintended to limit the scope of the invention. In particular the examplesdemonstrate representative examples of principles innate to theinvention and these principles are not strictly limited to the specificcondition recited in these examples. As a result it should be understoodthat the invention encompasses various changes and modifications to theexamples described herein and such changes and modifications can be madewithout departing from the spirit and scope of the invention and withoutdiminishing its intended advantages. It is therefore intended that suchchanges and modifications be covered by the appended claims.

A number of reaction products were produced using the reactants listedin FIG. 3, FIG. 4, and FIG. 5 according to the various methods describedbelow. The mass of surfactant added to all reactions was 5 g. Masses ofother reactants were calculated from the mole ratios described in FIGS.3, 4 and 5.

Hydroxy-Terminated Surfactants

Method I: A mixture of surfactant (di-hydroxy terminated) and hydrophobewas stirred and heated at 65° C. A solution of NaOH (50% in water) wasadded and the mixture left for 30 min at 65° C.Glycidoxypropyltrimethoxysilane was then added and the mixture left for2 h at 65° C. The reaction mixture was cooled then diluted to 5% w/w in20 g/L NaOH solution.

-   -   NaOH was added at 2 molar equivalents to that of added epoxide.    -   For A-O products, Method I was used excluding incorporation of        hydrophobe.        Amino-Terminated Surfactants

Method II: Surfactant was stirred and heated at 65° C. Hydrophobe wasadded and the mixture left for 30 min at 65° C.Glycidoxypropyltrimethoxysilane was then added and the mixture left for2 h at 65° C. The reaction mixture was cooled then diluted to 5% w/w in20 g/L NaOH solution.

-   -   For products P and Q, Method II was used excluding incorporation        of hydrophobe.

Method III: Surfactant was stirred and heated at 65° C. Epoxide binderwas added and the mixture left for 30 min at 65° C.Glycidoxypropyltrimethoxysilane was then added and the mixture left for2 h at 65° C. The reaction mixture was cooled then diluted to 5% w/w in20 g/L NaOH solution.

Method IV: A mixture of surfactant and amine binder was stirred andheated at 65° C. Epoxide binder was added and the mixture left for 30min at 65° C. Glycidoxypropyltrimethoxysilane was then added and themixture left for 2 h at 65° C. The reaction mixture was cooled thendiluted to 5% w/w in 20 g/L NaOH solution.

-   -   Products EE and FF were allowed to react for 60 min at 65° C.        prior to addition of the glycidoxypropyltrimethoxysilane.

Method V: A mixture of surfactant and amine binder was stirred andheated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 2 h total at 65° C. Glycidoxypropyltrimethoxysilane was thenslowly added and the mixture left for 1 h total at 65° C. The reactionmixture was cooled then diluted to 5% w/w in 20 g/L NaOH solution.

Method VI: A mixture of surfactant, amine binder and DMSO was stirredand heated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 3 h total at 65° C. Glycidoxypropyltrimethoxysilane was thenslowly added to the mixture. After 30 min a sample was taken from thereaction mixture and added slowly to a stirred 20 g/L NaOH solution,diluting the sample to a concentration of 13.3% w/w.

Method VII: A mixture of surfactant and amine binder was stirred andheated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 30 min total at 65° C. Glycidoxypropyltrimethoxysilane was thenslowly added to the mixture. After 19 min a sample was taken from thereaction mixture and added slowly to a stirred 20 g/L NaOH solution,diluting the sample to a concentration of 10% w/w.

Method VIII: A mixture of surfactant and amine binder was stirred andheated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 1 h total at 65° C. Glycidoxypropyltrimethoxysilane was thenslowly added to the mixture. After 15 min a sample was taken from thereaction mixture and added slowly to a stirred 20 g/L NaOH solution,diluting the sample to a concentration of 10% w/w.

Method IX: A mixture of surfactant, amine binder and DMSO was stirredand heated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 1 h total at 65° C. Glycidoxypropyltrimethoxysilane was thenslowly added to the mixture and the mixture left for 1 h. The reactionmixture was cooled then diluted to 10% w/w in 20 g/L NaOH solution.

Method X: A mixture of surfactant, amine binder and DMSO was stirred andheated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 3 h total at 65° C. Glycidoxypropyltrimethoxysilane was thenslowly added to the mixture. After 16 min a sample was taken from thereaction mixture and added slowly to a stirred 20 g/L NaOH solution,diluting the sample to a concentration of 11.8%.

Method XI: The reaction mixture from Method X was left at 65° C. for afurther 44 min post sampling, cooled then diluted to 11.8% w/w in 20 g/LNaOH solution.

Method XII: A mixture of surfactant, amine binder and DMSO was stirredand heated at 65° C. Epoxide binder was slowly added to the mixture thenleft for 2 h and 2 min total at 65° C. Glycidoxypropyltrimethoxysilanewas then slowly added to the mixture. After 20 min a sample was takenfrom the reaction mixture and added slowly to a stirred 20 g/L NaOHsolution, diluting the sample to a concentration of 11.8%.

Method XIII: The reaction mixture from Method XII was left at 65° C. fora further 40 min post sampling, cooled then diluted to 11.8% w/w in 20g/L NaOH solution.

Results: Test 1 Bottle Test Method

Assessment of inhibition of DSP formation used test conditions similarto those previously used and published. To a stirred sample of plantspent liquor, a small volume of concentrated sodium metasilicatepentahydrate solution was added slowly so as to increase the amount ofsilica in the liquor (typically the concentration was increased byapproximately 1 g/L as SiO₂). This “spiked” liquor was then split intobatches of 500 mL for treatment by addition of the appropriate inhibitorat the desired dose. One batch of spiked liquor was kept as untreatedliquor.

Each of the treated batches was then sub-sampled to deliver duplicatesamples which were individually placed into 250 mL Nalgene polypropylenebottles and placed into a rotating water bath at 95° C. Duplicateuntreated control samples were also included. After heating for 3 hours,the bottles were removed from the bath and the solids were collected byfiltration, washed with hot water and dried in the oven at 110° C. Afterdrying the resulting mass of DSP solids precipitated was weighed. Theefficacy of the treatment was determined by comparing the mass of DSPprecipitated from the individual treated samples to the untreatedcontrol samples in the same test.

Results are presented as a percent calculated as: (Average masstreated/Average mass untreated)×100. A value of 100% means no effectiveinhibition (same mass as untreated) while a value less than 100%indicates some inhibitory activity. Lower numbers indicate moreeffective inhibition.

Type 1.1 Ethoxylated Alcohol Surfactant/Siloxane

TABLE 1 % Sodalite Precipitated Dose (ppm) Product 80 120 160 A 88 75 A*78 73 A* 66 57 B 72 61 C 72 61 D 69 45 E 70 61 61 *test repeated underthe same test conditions as previousType 1.2 Ethoxylated Amine Surfactant/Siloxane

TABLE 2 % Sodalite Precipitated Dose (ppm) Product 80 120 160 200 220 F77 91 G 6 0.6 H 16 2 H* 8 2 1 H* 11 2 0.8 J 91 58 K 36 11 L 17 4 M 23 6M* 28 5 4 M* 25 6 N 27 7 O 30 4 *test repeated under the same testconditions as previousType 1.3 Fatty Amine Surfactant/Siloxane

TABLE 3 % Sodalite Precipitated Dose (ppm) Product 40 80 120 P 59 16 7 Q43 58 48Type 2.1 Ethoxylated Amine Surfactant/Siloxane/Hydrophobe

TABLE 4 % Sodalite Precipitated Dose (ppm) Product 80 120 R 95 101 S 7181 T 33 9 T* 32 6 *test repeated under the same conditions as previousType 2.2 Fatty Amine Surfactant/Siloxane/Hydrophobe

TABLE 5 % Sodalite Precipitated Dose (ppm) Product 40 80 120 U 13 9 U*56 28 7 V 86 72 *test repeated under the same conditions as previousType 3.1 Fatty Amine Surfactant/Siloxane/Epoxide Binder

TABLE 6 % Sodalite Precipitated Dose (ppm) Product 20 40 80 100 120 140X 37 3 1 Y 22 4 0.2 Y* 58 28 13 8 4 3 Y* 15 1.5 0.4 Z 27 13 5 ZA 52 3 3*test repeated under the same conditions as previous testsType 4.1 Fatty Amine Surfactant/Siloxane/Amine Binder/Epoxide Binder

TABLE 7 % Sodalite Precipitated Dose (ppm) Product 10 20 40 60 80 140 AA57 11 4 BB 25 4 0.1 CC 78 45 0.7 DD 12 0 0 DD* 90 73 18 0 0 EE 84 59 9FF 49 0 0 FF* 93 85 46 9 0 *test repeated under the same conditions aspreviousResults: Test 2 Bottle Test Method

Test 2 conditions were similar to those of Test 1 but were designed toassess the effect on the initial formation of DSP solids from solution.As a result, a shorter holding time for the precipitation step and anincreased initial concentration (higher “spike”) of silica in the liquorwas used in this method. Data is again presented as a percent of massprecipitated compared to an undosed control sample.

Type 4.2 Fatty Amine Surfactant/Siloxane/Pentamine Binder/Epoxide Binder

TABLE 8 % Sodalite Precipitated Dose (ppm) Product 25 45 50 JJ 36 DS 400 ES 18 0 FS 55 24 GS 50 12

TABLE 9 % Sodalite Precipitated Dose (ppm) Product 20 25 30 40 45 50 6080 100 200 400 SA 71 62 SB 41 1.8 1 SC 36 2.5 SD 59 7 SE 23 3.4 SF 12.82.3 SG 45 0 SH 78 57 SI 0 0 SJ 26 0.3 SK 70 27 SL 7 2 SM 77 0 0 SN 15637 SO 24 14 SP 97 77 3.6 0 SQ 82 62 1.5 0 SR 69 28 ST 78 33 2 0 SU 74 770 0 SV 30 4 SW 56 27 0.5 SX 41 2 AS 70 12 BS 40 3.3 CS 32 0 DS 40 0 ES18 0 FS 55 24 GS 50 12 HS 31 0Type 4.3 Fatty Monoamine Surfactant/Siloxane/Pentamine Binder/EpoxideBinder

TABLE 10 % Sodalite Precipitated Dose (ppm) Product 20 40 LL 44 42 MM 4741Test 2—Surfactant-Based Molecules Versus Gen 2 and Gen 3

TABLE 11 % Sodalite Precipitated Dose (ppm) Product 20 25 30 50 100 200400 500 800 1100 1200 Gen2 106 114 76 39 40 37 Gen3 88 92 81 55 32 32 DD103 79 41 1 HS 58 16 0Results in table 11 above demonstrate the surprising difference betweenthe inhibitory effects of previously identified small moleculeinhibitors (Gen 2 and Gen 3 products) and surfactant based products (DDand HS). The latter are effective in eliminating DSP formation at dosesas low as 30 ppm. However, for the Gen 2 and Gen 3 products some DSPprecipitation still occurs under these test conditions even at dosesgreater than 1000 ppm. Given the efficacy of the Gen 2 and Gen 3products under test 1 conditions, such a result is unexpected and novel.Results: Test 3—Metal Coupon Test

Test 3 conditions were the same as test 2 however, metal coupons wereincluded in the bottles and small amounts of DSP were precipitated ontothe surface of the metal. As shown in FIG. 6, SEM analysis of coupontests using the invention shows that significant amounts of DSP wereprecipitated onto the untreated coupon, as well as those treated withextreme doses (1000 ppm) of GEN2 and GEN3 products. However, on thecoupon subjected to liquor treated with the surfactant based inhibitor(KK) at relatively low dose (100 ppm) significantly less DSP wasdeposited. This indicates substantial and surprising efficacy of thesurfactant based small molecule in inhibiting the formation of DSPscale.

TABLE 2.15 Treatment of liquor exposed to metal coupons in test method3. Coupon Product type Product Dose (ppm) I No Treatment N/A N/A IIProduct Type D GEN2 1,000 III Product Type E GEN3 1,000 IV Product Type4.2 KK 100

While this invention may be embodied in many different forms, there aredescribed in detail herein specific preferred embodiments of theinvention. The present disclosure is an exemplification of theprinciples of the invention and is not intended to limit the inventionto the particular embodiments illustrated. All patents, patentapplications, scientific papers, and any other referenced materialsmentioned herein are incorporated by reference in their entirety.Furthermore, the invention encompasses any possible combination of someor all of the various embodiments mentioned herein, described hereinand/or incorporated herein. In addition the invention encompasses anypossible combination that also specifically excludes any one or some ofthe various embodiments mentioned herein, described herein and/orincorporated herein.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to”. Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein which equivalents are also intended to be encompassedby the claims.

All ranges and parameters disclosed herein are understood to encompassany and all subranges subsumed therein, and every number between theendpoints. For example, a stated range of “1 to 10” should be consideredto include any and all subranges between (and inclusive of) the minimumvalue of 1 and the maximum value of 10; that is, all subranges beginningwith a minimum value of 1 or more, (e.g. 1 to 6.1), and ending with amaximum value of 10 or less, (e.g. 2.3 to 9.4, 3 to 8, 4 to 7), andfinally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 containedwithin the range. All percentages, ratios and proportions herein are byweight unless otherwise specified.

This completes the description of the preferred and alternateembodiments of the invention. Those skilled in the art may recognizeother equivalents to the specific embodiment described herein whichequivalents are intended to be encompassed by the claims attachedhereto.

The invention claimed is:
 1. A method of reducing aluminosilicatecontaining scale in a Bayer process comprising: adding to a Bayer liquora non-polymeric reaction product resulting from the reaction ofdodecyl-1,3-propanediamine, tetraethylenepentamine, ethylenediamine, andan epoxide binder; and a glycidoxyalkyltrimethoxysilane.
 2. The methodof claim 1, wherein the epoxide binder is selected from epichlorohydrinand ethylene glycol diglycidylether.
 3. The method of claim 1, whereinthe epoxide binder is epichlorohydrin.
 4. The method of claim 1, whereinthe epoxide binder is ethylene glycol diglycidylether.
 5. The method ofclaim 1, wherein the glycidoxyalkyltrimethoxysilane is3-glycidoxypropyltrimethoxysilane.
 6. The method of claim 1, wherein theepoxide binder is a molecule according to formulas (I), (II), and anycombination thereof:


7. The method of claim 1, wherein the epoxide binder is a compositionaccording to formula (I):


8. The method of claim 1, wherein the epoxide binder is a compositionaccording to formula (II):


9. The method of claim 1, the non-polymeric reaction product resultingfrom the reaction of items further comprising a hydrophobe, wherein thehydrophobe is a C8-C10 aliphatic glycidyl ether.
 10. The method of claim1, wherein the non-polymeric reaction product has a molecular weight ofless than 500 daltons.
 11. The method of claim 1, wherein thenon-polymeric reaction product is formed according to one of the methodsselected from the group consisting of Methods I, II, III, IV, V, VI,VII, VIII, IX, X, XI, XII, and XIII, and any combination thereof. 12.The method of claim 1, wherein the non-polymeric reaction product isadded to the Bayer liquor upstream of or at a heat exchanger.
 13. Themethod of claim 1, wherein the dodecyl-1,3-propanediamine, thetetraethylenepentamine, the ethylenediamine, the epoxide binder, and theglycidoxyalkyltrimethoxysilane are reacted at a molar ratio of about2:1:1:3:1, respectively.
 14. The method of claim 1, wherein thedodecyl-1,3-propanediamine, the tetraethylenepentamine, theethylenediamine, the epoxide binder, and theglycidoxyalkyltrimethoxysilane are reacted at a molar ratio of about2:1:1:3:2, respectively.
 15. The method of claim 1, wherein thedodecyl-1,3-propanediamine, the tetraethylenepentamine, theethylenediamine, the epoxide binder, and theglycidoxyalkyltrimethoxysilane are reacted at a molar ratio of about2:1:1:3:3, respectively.